Many antibiotics are already known but new antibiotic substances are still demanded to be provided in the pharmaceutical field and also in the agricultural field. Compounds which are similar in their structural feature of the molecule to the new antifungal and antiviral antibiotic, N-acetylbenanomicin B now newly provided by the present inventors are benanomicin A and benanomicin B as well as dexylosylbenanomicin B which have hithertobefore been obtained as new compounds by the present inventors (see Japanese patent applications Nos. 277,692/87 and 327,163/87 as laid-open under Japanese patent application first publications "Kokai" No. 121,293/83 published on 12 May, 1989 and No. 254,694/89 published on 11 October 1989, respectively, as well as their corresponding European patent application publication No. 0 315 147 A2 published on 10 May 1989 and corresponding U.S. patent application Ser. No. 264,888 filed on 31 October 1988 now U.S. Pat. No. 5,055,453). Furthermore, KS-619-1 substance [Matsuda et al: the "Journal of Antibiotics" 40, 1104-1114(1987)], G-2N substance and G-2A substance [Gerber et al: "Canada. J. Chem," 62, 2818-2821 (1984)] as well as pradimicins A, B and C [Oki et al: "Journal of Antibiotics" 41, 1701-1704 (1988); Tsunakawa et al: "J. Org. Chem." 54, 2532-2536 (1989); and European patent application publication No. 0 277 621] are already known. Among them, benanomicin B seems to be identical to pradimicin C by their structural studies.
Hithertobefore, a variety of antibiotics which are produced by microorganisms are already known. Among the known antibiotics, however, such antibiotics which can exhibit a useful antifungal activity but a low toxicity to mammals are only few. Accordingly, there is always a demand for discovery and exploitation of a new antifungal antibiotic which is useful in the therapeutic treatment of various fungal infections in an animal, including human.
On the other hand, acquired human immunodeficiency syndrome (sometime called merely as "AIDS") has been found to be a disease which is caused due to human T-cells being infected by a causative virus in human blood. The virus which is causative of the acquired human immunodeficiency syndrome is usually termed as acquired human immunodeficiency syndrome virus which is often abbreviated as HIV. It has been reported that certain known compounds are useful as an agent for inactivating HIV or an antiviral agent against HIV. However, any of these compounds is not necessarily satisfactory as a useful remedial agent for AIDS, and there is a strong outstanding demand to develope and provide such a new drug which shows a low toxicity but can show a high activity to inactivate HIV and which are expectable as a useful medicinal agent for therapeutically or preventively treating AIDS.
According to some inventions which are earlier made by the present inventors, there are provided two antibiotics, benanomicin A and benanomicin B, which each have an antifungal activity and an HIV-inactivating activity, as well as a process for the production of benanomicins A and B by cultivation of an actinomycete strain MH193-16F4 (deposited under FERM BP-2051)(see the above-mentioned European patent application publication No. 0 315 147 A2 and its corresponding U.S. patent application Ser. No. 264,888 now U.S. Pat. No. 5,055,453). Furthermore, there is provided a pharmaceutical compositions for inactivating HIV virus, which comprises benanomicin A or benanomicin B as active ingredient (see Japanese patent application No. 206346/88, filed on 22 August 1988 and its corresponding European patent application No. 89.402315.9 filed on 21 August 1989 and corresponding U.S. patent application Ser. No. 394,539 filed on 16 August 1989). The chemical structure of benanomicin B is shown by the following formula (II) ##STR1##